High-yield magnetic recoil neutron spectrometer on the National Ignition Facility for operation up to 60 MJ

M Gatu Johnson; T M Johnson; B J Lahmann; F H Séguin; B Sperry; N Bhandarkar; R M Bionta; E Casco; D T Casey; A J Mackinnon; N Masters; A Moore; A Nikroo; M Hoppe; R Mohammed; W Sweet; C Freeman; V Picciotto; J Roumell; J A Frenje

doi:10.1063/5.0099317

High-yield magnetic recoil neutron spectrometer on the National Ignition Facility for operation up to 60 MJ

Rev Sci Instrum. 2022 Aug 1;93(8):083513. doi: 10.1063/5.0099317.

Authors

M Gatu Johnson¹, T M Johnson¹, B J Lahmann¹, F H Séguin¹, B Sperry¹, N Bhandarkar², R M Bionta², E Casco², D T Casey², A J Mackinnon², N Masters², A Moore², A Nikroo², M Hoppe³, R Mohammed³, W Sweet³, C Freeman⁴, V Picciotto⁴, J Roumell⁴, J A Frenje¹

Affiliations

¹ Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
² Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
³ General Atomics, San Diego, California 92186, USA.
⁴ State University of New York at Geneseo, Geneseo, New York 14454, USA.

PMID: 36050054
DOI: 10.1063/5.0099317

Abstract

Recent progress at the National Ignition Facility (NIF), with neutron yields of order 1 × 10¹⁷, places new constraints on diagnostics used to characterize implosion performance. The Magnetic Recoil neutron Spectrometer (MRS), which is routinely used to measure yield, ion temperature (T_ion), and down-scatter ratio (dsr), has been adapted to allow measurements of dsr up to 5 × 10¹⁷, and yield and T_ion up to 2 × 10¹⁸ in the near term with new data processing techniques and conversion foil solutions. This paper presents a solution for extending MRS operation up to a yield of 2 × 10¹⁹ (60 MJ) by moving the spectrometer outside of the NIF shield wall. This will not only enhance the upper yield limit by 10× but also improve signal-to-background by 5×.